Press



May 23, 1967 c. J. HAMKINS PRESS Filed July 2, 1965 5/ a MW United States Patent 3,320,740 PRESS Clark J. Hamkius, Racine, Wis., assignor to Walker Manufacturing Company, a corporation of Delaware Filed July 2, 1965, Ser. No. 469,086 1 Claim. (Cl. 6026.1)

This invention relates to a press for cutting or forming workpieces and more particularly to an explosively operated device for actuating such a press.

It is an object of this invention to provide an explosively actuated press.

It is a further object of the invention to provide an improved driving mechanism for an explosively actuated press.

It is a still further object of the invention to provide improved valve devices for an explosively actuated press that do not require additional operating mechanisms.

It is a still further object of the invention to provide an improved driving structure that incorporates an integral means for compressing the air within the explosive press.

An explosively actuated press embodying this invention comprises a power ram adapted to carry a tool and has means supporting the ram for reciprocation of the tool into engagement with a workpiece. The ram is actuated by relatively movable piston and cylinder members one of which is interconnected to the ram for reciprocally driving the ram. Means are provided for charging the space b tween the piston member and the cylinder member with a stoichiometric fuel-air mixture when the members are in a first position prior to an operative stroke of the ram. Means are provided for igniting the stoichiometric mixture to drive the ram, for returning the ram to its first position and for exhausting the fired mixture from the space between the members.

Other objects and advantages of the invention will become more apparent as this description proceeds, particularly when considered in conjunction with the accompanying drawings, wherein:

FIGURES 1 through 3 are partially schematic crosssectional views of an explosive press embodying this invention and show the press in various positions.

FIGURE 1 illustrates the press in a charged position prior to an operative stroke.

FIGURE 2 illustrates the press at the completion of an operative stroke.

FIGURE 3 illustrates the press in an intermediate position prior to the return to the charged position.

Referring now in detail to the drawings, a press embodying this invention comprises a ram 11 adapted to carry a tool 12 which in turn engages a workpiece (not shown) supported upon a die 13. It is to be understood the tool 12 and die 13 may be of any known type or the ram 11 may be used to perform any type of forming operation.

An explosive or internal combustion driving device 14 is provided for driving the ram 11 through an operative stroke into engagement with the workpiece. The driving device 14 comprises a cylinder assembly, indicated generally by the reference numeral 15, defining an axially extending cylinder bore 16 that is concentrically disposed with respect to the ram 11. The upper end of the cylinder assembly 15 is closed by a cylinder head 17 and the lower end is closed by a base portion 18 in which a cylindrical bore 19 is formed. The cylindrical bore 19 guidingly engages the ram 11 and supports it for reciprocation, the cylinder 15 being supported in a fixed position with respect to the die 13 in any known manner.

A piston member 21 is supported for reciprocation within the cylinder bore 16 and divides it into first and second confined spaces or chambers 22 and 23 respectively. The ram 11 is formed integrally with the piston member 21 and thus functions as a piston rod for the piston 21. Alternatively, the ram 11 may be connected in any known manner to the piston 21.

A coil compression spring 24 encircles the ram 11 and engages the lower side of the piston 21 and the upper side of the cylinder base portion 18. The coil spring 24 normally urges the piston 21, ram 11 and tool 12 to an upward or first position at the completion of the operating stroke of the ram 11 and in a charged position for the next operating stroke.

Air under pressure is delivered to the cylinder head 17 by means of an air inlet conduit 25 from a source of air under pressure, as will become more apparent as this description proceeds. The conduit 25 is fitted into a transversely extending passage 26 formed in the cylinder head 17. The passage 26 is intersected by an enlarged bore 27 formed at the upper end of a smaller bore 28. The bore 28 is intersected by a diagonal bore 29 that extends into the chamber 2 2 formed between the head of the piston 21 in the upper portion of the cylinder assembly 15.

A valve member comprise-d of an elongated operating portion 31 and an enlarged head portion 32 controls the flow or air from the passage 26 into the cylinder chamber 22 through the passage 29. The valve operating portion 31 extends coaxially within the bore 28 but is smaller in diameter than it. The cylinder head has a reduced diameter bore 32 that slidably engages the valve operating portion 31 to support it for reciprocation. The head portion 32 is adapted to be received in the bore 27 and is larger in diameter than the bore 28 to shut off the flow through it.

At the opposite side of the cylinder head 17, a similar valve device is provided for admitting fuel to the chamber 22 to form a stoichiometric fuel-air mixture therein. The fuel admission means comprises a conduit 34 that is connected to a source of pressurized fuel 35, for example propane under pressure, by means of a pressure control valve 36. The conduit 34 opens into a passage 37 formed in the cylinder head 17. The passage 37 is intersected by an enlarged bore 38 formed at the upper end of a smaller bore 39. An operating portion 41 of a valve element is supported in a cylindrical bore 42 formed in the cylinder head 17 at the base of the bore 39. The valve operating portion 41 terminates in an enlarged head portion 43 that is adapted to engage the shoulder between the bores 38 and 39 to preclude passage of fuel from the passage 37 into the chamber 22 through a transverse passage 44 that intersects the bore 39.

Burnt fuelair mixture is discharged from the chamber 22 through an exhaust port 45 in the form of a cylindrical passage disposed in the cylinder head 17 concentrically with the cylinder bore 16. The exhaust port 45 is intersected by a diagonally extending passage 46 which communicates to the atmosphere through any suitable type of silencing device (not shown). A pressure responsive exhaust valve controls the flow through the exhaust port 45. The exhaust valve has an enlarged head portion 47 that is adapted to abuttingly engage the lower surface of the cylinder head 17 and close off the mouth of the passage 45. A stern portion 48 of the exhaust valve extends through and is slidably supported by a mating bore 49 formed in the cylinder head 17. The stem portion 48 has an enlarged portion 51 at its upper end to preclude the valve from falling into the cylinder and to limit the degree to which it opens. A coil spring 52 encircles the exhaust valve stem portion 48 and engages the cylinder head 17 and the head portion 47 to normally urge the exhaust valve -to an open position. A coil spring 53 is afiixed to the head of the piston 21 and is adapted to engage the exhaust valve head 47 under certain circumstances to close it.

A spark plug 54 is threaded into the cylinder head 17 and has its spark gap exposed within the chamber 22. The

spark plug 54 may be fired by means of any suitable high tension coil and timing mechanism to ignite the mixture formed within the chamber 22.

Operation The press is preconditioned for an operative stroke of the ram by the coil spring 24 urging the piston 21 to an uppermost position (FIGURE 1). In such position the head of the piston 21 contacts the air and fuel valve operating portions 31 and 41 to move the valve heads 32 and 43 away frorntheir seats. Air under pressure then enters the cylinder chamber 22through the passages 26, 2S and 29 and fuel enters thecylinder chamber 22 through the passages 37, 38, 39 and 44. The pressure of the fuel and air sources are regulated to a stoichiometric fuelair mixture within the cylinder chamber 22 when both fuel and air valves are opened. At this time, the coil spring 53 overcomes the action of the coil spring 52 to hold the exhaust valve head 47 against its seat.

To initiate a press or punching operation, the spark plug 54 'is fired. This ignites the mixture within the chamber 22 and causes a rapid combustion or an explosion that abruptly increases the pressure within chamber 22. The piston and ram 11 are then urged downwardly whereby the piston head 21 no longer contacts the valve operating portions 31 and 41. The fuel and air valves then will close. It is to be understood that springs (not shown) may be provided to assist the closing of the valves. As the piston 21 is driven downwardly, the

increased pressure within the chamber 22 acting upon the exhaust valve head 47 holds it in its closed position against the action of the spring 52 (FIGURE 2). During the downward movement of the piston 21, the coil spring 24 is compressed until the tool 12 strikes the workpiece upon the die 13.

After the expansion has taken place, the pressure in the chamber 22 decreases sufficiently to permit the spring 52 to urge the exhaust valve head portion 47 away from its seat (FIGURE 3). The coil spring 24 also urges the piston 21 upwardly at this time, causing the burnt mixture to be exhausted from the chamber 22 through the passages 45 and 46. When the piston 21 again reaches its uppermost position (FIGURE 1), the chamber v22 .can be charged for the next initiation of the press stroke.

As has been noted, the cylinder chamber 22 is charged with air under pressure. The compression of the volume within the chamber 23 during the descending motion of the piston 21 is utilized to compress the air for delivery to the chamber 22. For this purpose a conduit 61 extends into the chamber 23 through the wall of the cylinder assembly 15 at a point below the bottom dead center position of the piston 21. The conduit 61 is connected to an atmospheric inlet passage 62 by means of a check valve 63. The conduit 61 also is interconnected to a conduit 64 in which a check valve 65 is provided. The conduit 65 is interconnected to a pressure accumulator device 66 by means of a conduit 67 and to a pressure regulator valve 68 that discharges into the conduit 25. A pressure indicating gauge 69 may be positioned upstream from the pressure regulator valve 68 so that the pressure which enters the cylinder chamber 22 may be read.

When the piston 21 is in the position shown in FIG- URE 1, the check valve 63 can be opened and the check valve 65 is closed. Air may then flow under pressure from the accumulator 66 into the cylinder chamber 22. Atmospheric air may also flow into the cylinder space 23 through the conduit 62 and check valve 63 at this time. when the piston 21 is ascending. When the mixture within the chamber 22 is fired and the piston 21 begins its downward stroke, the check valve 63 will close. When the pressure in the chamber 23 exceeds that at which the check valve 65 opens, air will be delivered under pressure to the accumulator 66. If desired an auxiliary air Although most of the air intake will take place 7 source (not shown) can also be added to charge the accumulator 66.

While it will be apparent that the preferred embodiments of the invention disclosed are Well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claim.

What is claimed is:

An explosively actuated press or the like comprising a power ram adapted to carry a tool, a work supporting base for supporting a workpiece adapted to be engaged by the tool, a cylinder, a piston supported for reciprocation within said cylinder and dividing said cylinder into two chambers on opposite sides of said piston, means afiixing said cylinder with respect to said work supporting base, means affixing said piston to said ram for driving said ram, means for charging one of said chambers with a stoichiometric fuel-air mixture, said means comprising inlet passage means formed in said cylinder and opening into said one chamber and inlet valve means supported for reciprocation by said cylinder having an enlarged head portion adapted to control the flow through said inlet passage means, said inlet valve means having an integral portion extending from said head portion into said one chamber and adapted to be engaged by said pis-v ton when said piston is in a first position for opening said inlet valve means, exhaust passage means extending through said cylinder from said one chamber to the atmosphere for discharging a burnt charge from said one chamber, exhaust valve means supported for reciprocation by said cylinder for controlling the flow through said ex haust passage means, said exhaust valve means having an enlarged head portion exposed to the pressure within said one chamber and adapted to control the passage of exhaust gases through said exhaust gas passage means, biasing means cooperating with said enlarged head portion of said exhaust valve means for urging said exhaust valve means to an open position, spring means carried by said piston and adapted to engage said exhaust valve head portion and urge said exhaust ,valve to its closed position when said piston is in its first position, biasing means disposed in the other chamber of said cylinder and engaging said piston for urging said pitson to said first position, means for firing the stoichiometric fuelair mixture in said one chamber for urging said piston from said first position to a second position wherein the tool carried by said ram is adapted to engage a workpiece supported upon said work supporting base, an air accumulator, conduit means interconnecting said air accumulator to said inlet passage means for delivering air under pressure to said inlet passage means, and valved passage means interconnecting saidother chamber with the atmosphere and with said accumulator for drawing air from the atmosphere into said other chamber upon movement of said piston from its first position to its second position and for delivering air under pressure to said accumulator upon movement of said piston from its first position to its second position.

References Cited by the Examiner UNITED STATES PATENTS 588,062 8/1897 Hart 12346 1,597,924 8/1926 Powell 123-27 2,898,893 8/1959 Rohrer et al. 6026.1 3,012,549 12/1961 Bard et al. 123-46 3,042,008 7/1962 Liesse 123-46 3,213,607 10/1965 Neumeier 60-26.1

MARK NEWMAN. Primary Examiner.

WENDELL E. BURNS. Examiner. 

